1. Field of the Invention
The present invention relates to information processing of transmitting multimedia contents through a computer network.
2. Description of the Related Art
Conventionally, RFC 3986 released by the Internet Engineering Task Force (IETF) defines a method of describing a uniform resource identifier (URI) for identifying a resource such as a file on a network. According to this definition, the user of a URI can express a subordinate resource such as partial data of a main resource by adding a description called a fragment identifier as part of the URI.
Furthermore, the World Wide Web Consortium (W3C) is developing the specifications of a media fragment URI representing, with a fragment identifier, data obtained by fragmenting a multimedia content such as a moving picture in terms of a time, coordinate, or track type (image, audio, subtitles, and the like). According to the specifications, when acquiring a moving picture from an apparatus for distributing a moving picture, a terminal apparatus for playing back a moving picture or the like can designate part of the moving picture as an acquisition target using a URI including a fragment identifier.
If a resource to be acquired is on a Web server, hypertext transfer protocol (HTTP)/1.1 defined as a communication protocol in RFC 2068 is often used.
On the other hand, if a surveillance camera connected to a network has a small storage capacity for data storage, it segments recorded video data by a predetermined data size or a predetermined time interval, and uploads the segmented recorded video data as separate files to a server used for data storage. If the server used for data storage has a Web server function, the user of the surveillance camera uses a Web browser to issue a request to transmit the stored files as video contents.
Furthermore, video data of a specific location or event, which have been shot by a plurality of cameras, are often uploaded as separate files to a storage service provided as a cloud service. If the storage service has a Web server function, the user of the service uses a Web browser to issue a request to transmit the stored files as video contents.
If, however, a request range of a video content is designated by a media fragment URI description, that is, segment data of a video content is requested, data for the request range may not exist in the video content. In the above surveillance camera example or storage service example, segment data for the request range exist not in a file (to be referred to as a designated file hereinafter) designated by a media fragment URI but in a different file.
Even if the segment data for the request range exists, if it is in another file, the Web server cannot identify the relation between the designated file and the other file, and thus cannot specify the segment data. Consequently, the Web server cannot acquire the segment data for the request range from the video content of the designated file, and thus replies an error message to the Web browser, or supplies the whole video content of the designated file to a client on which the Web browser operates in order to delegate subsequent processing to the Web browser. In other words, the Web browser cannot acquire the data even though the segment data for the request range exists in the Web server.